This invention relates to shipping and storage pallets and more particularly to pallets having a plastic construction.
Pallets have traditionally been formed of wood. Wood pallets, however, have many disadvantages. For example, they are subject to breakage and thus are not reusable over an extended period of time. They are also difficult to maintain in a sanitary condition, thus limiting their usability in applications where sanitation is important such, for example, as in food handling applications.
In an effort to solve some of the problems associated with wood pallets, plastic pallets have been employed with some degree of success. Specifically, although the plastic pallets heretofore employed have been durable, have been reusable over an extended period of time and have been easy to maintain in a sanitary condition, they have suffered from the disadvantage of costing considerably more than the comparable wooden pallets, thereby limiting their commercial acceptance. Although manufacturing costs are reflected in the cost of the plastic pallets, the main reason that the plastic pallets cost considerably more than the comparable wooden pallets is that they require a given amount of relatively expensive plastic material for a given measure of pallet strength and the required plastic material has a given cost that constitutes a substantial portion of the total cost of the pallet.
Certain of the prior art plastic pallets have also suffered from the disadvantage that they do not provide a smooth upper pallet surface but rather provide major hollows or concavities in the pallet load surface which interfere with the loading of small objects on the surface and tend to collect dirt and debris. For example, in one generally successful form of plastic pallet design, a twin sheet construction has been used in which upper and lower plastic sheets are formed in separate molding operations and the two sheets are then selectively fused or knitted together in a suitable press to form a reinforced double wall structure. Whereas such twin sheet plastic pallets have been generally satisfactory, they typically define large concavities in the pallet surface which interfere with the loading of small objects on the pallet and encourage the collection of debris in the concavities.